--- ksh-openbsd_cvs/sh.h	2010-02-23 12:49:21.000000000 +0100
+++ ksh-openbsd_cvs.new/sh.h	2010-04-01 21:01:24.135232661 +0200
@@ -16,6 +16,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdlib.h>
+#define __USE_GNU /* needed for setresuid() and setresgid() */
 #include <unistd.h>
 #include <string.h>
 #include <stdarg.h>
